Longspine Urchin

Longspine Urchin (Diadema setosum / Diadema antillarum) The Longspine Urchin is a fascinating and highly beneficial marine invertebrate prized for its exceptional algae-grazing abilities and striking appearance. With its long, slender black spines radiating from a small central body, this echinoderm creates a dramatic display while serving as one of the most effective members of a reef aquarium cleanup crew. Active primarily during the evening and nighttime hours, the Longspine Urchin constantly grazes on nuisance algae, helping maintain clean rockwork and a healthy reef ecosystem. Native to tropical coral reefs throughout the Indo-Pacific and Caribbean, Longspine Urchins inhabit rocky reef slopes, lagoons, and coral outcroppings where they shelter in crevices during the day and emerge to feed after dark. In the home aquarium, they thrive in mature reef systems with abundant live rock, stable water parameters, and plenty of natural algae to graze. Their long spines require adequate space to move freely, so care should be taken when placing corals nearby. Longspine Urchins are herbivores that primarily consume filamentous algae, film algae, and biofilm growing on live rock and aquarium surfaces. If natural algae become scarce, they should be supplemented with dried nori, algae wafers, or other marine algae-based foods to ensure proper nutrition. These peaceful invertebrates are completely reef safe with corals but may occasionally carry loose shells, rubble, or small unsecured frags on their spines as camouflage. They are excellent companions for reef-safe fish, snails, shrimp, starfish, and other cleanup crew members. Aquarists should exercise caution when handling them, as their sharp spines can easily puncture skin. Scientific Name: Diadema setosum / Diadema antillarum Common Name: Longspine Urchin, Long-Spined Sea Urchin Care Level: Moderate Temperament: Peaceful Diet: Herbivore Adult Size: Body Up to 4 Inches (Spines Can Exceed 10 Inches) Minimum Tank Size: 50 Gallons Origin: Indo-Pacific or Caribbean (Species Dependent) Reef Safe: Yes If you're looking for an eye-catching cleanup crew member with outstanding algae-control abilities, the Longspine Urchin is an exceptional choice. Its unique appearance, constant grazing behavior, and reef-safe nature make it a valuable addition to mature saltwater reef aquariums.